Major Lutz has been delivering parts of the rocket that he has been working on to the underground, meeting his contact in town. This time, he cannot give them the device because it came from the model that will be tested in a few days and the part cannot go missing without the Gestapo becoming suspicious. For this part, he asks the underground to get him out of Germany. What makes this difficult is that every man in his department is being watched, including Major Lutz. His underground contact, Lila Fenster, agrees to talk to her contact to see if there is a way out.

Lila comes to talk to Colonel Hogan to see if he has any ideas. She wants him to get Lutz into camp so they can get him out via the tunnel. Colonel Hogan assures Lila that he'll think of something. "That's good", she says. "No, I always say that when I can't think of a thing!"

Meanwhile, Carter is building a rabbit trap to catch some hassenpfeffer. It's a pretty "hi-tech" rabbit trap, and he demonstrates it to the gang. With a hat playing the part of a rabbit, he demonstrates how the rabbit will get caught. Hogan's response, "If we were fighting rabbits, the war would be over right now."

At this point, Schultz walks in. Without missing a beat, Hogan asks his men when the gonculator would be finished. The men play along and complain about finding the parts necessary to finish. They then "notice" Schultz and try to hide the gonculator. When Schultz inquires, they tell him it's a rabbit trap, but he's not buying it. Humoring them, he feigns being tired and rushes out of the barracks to "take a nap". Hogan and his men know that he's off to tell Klink what he found. Hogan tells his men, "I don't know whether this thing will catch a rabbit, but it sure works great with pigeons!"

Klink didn't want to be disturbed while he was doing his paperwork. When Schultz tries to tell him about the gonculator, Klink sends him away withouth letting him get a word in edgewise to tell him what he found. "The General Staff is waiting to find out how many paper napkins we use. They can't go on with the war until they find that out. Diiiiiiis-miiiissed."

As Schultz is leaving, Hogan comes in. Klink tries to shoo him away, but Hogan is a little more forceful than Schultz and lays on the psychology with Klink. "Fine, I'll tell them that the insult to you, that they (the men) are taking personally, isn't bothering you at all." This peaks Klink's curiosity and he tells Hogan to come back in and tries to get him to tell him what the insult is. Hogan plays it out, refusing to "come to the point".

Finally, Hogan does, and asks Klink if he knows Major Lutz, the well known German electronics expert. Klink doesn't, but acts like he does because he doesn't want to show Hogan he doesn't know. Hogan tells him that Lutz has invented a new electronic prisoner escape device and it's being installed in Stalag 19. Klink doesn't believe it, but Hogan talks him into doing something about it.

But instead of doing it today, he has to do it tomorrow because he still has to finish the paperwork. Hogan offers him a solution, that he used to use when he was working in the pentagon: Assign all the papers to the attention of Colonel John Smith and send them off. "You expect me to write 'Attention Colonel John Smith' and have someone on the pentagon do my work for me?" Hogan laughs "Glad to see you haven't lost your old sense of humor. No, obviously in your case you would write Colonel Johann Schmidt" Klink doesn't buy it and dismisses Hogan. But when Hogan leaves the room, Klink assigns all his work to Colonel Johann Schmidt and is done in no time!

Schultz returns as Klink is cleaning his desk. He now can report on the gonculator. Before Schultz can start, the phone rings. It's General Burkhalter. He's coming for an inspection later and he wants everything ready. He doesn't want to spend any more time than necesary in the camp. "I understand sir, a word to the wise", to which the General replies "I wouldn't call it that." Klink then asks why Stalag 19 received the electronic prisoner escape device when Stalag 13 has a better record than them. The General doesn't have any idea what he's talking about, but says that if they got it, it's because they have escapes and Klink doesn't. As with everything Burkhalter says, Klink agrees completely.

After hanging up, Schultz can (finally) go on with his report. As he is doing so, Hogan and the boys are listening in on the coffee pot. He tells Klink that Hogan and his men were building a gonculator. The expression on Klink's face is priceless, "A what?" Schultz relays everything, and Klink is still not sure what he's talking about. Finally, he gets indignant "Imagine the nerve of that Hogan. Thinking he can build a gonculator right under my nose." Meanwhile, Hogan has Kinch get every spare radio part they have. They are really going to build a gonculator.

Klink and Schultz then pay a visit to the barracks and Klink tells Hogan to take all his men to the motorpool to clean up for the inspection. Hogan wants to leave one man behind to tidy up, but Klink insists on all men. After the men are gone, Klink and Schultz look for the gonculator. They find it right where Hogan wanted him to, in one of the men's footlocker. When they find it, Klink confirms that it is a gonculator, though it looks different from the German verison. (Rather funny, since Klink doesn't even know what a gonculator is!) Schultz asks to smash it, but Klink wants to show it to General Burkhalter.

The General visits and Klink tells him about the surprise. As Klink is giving his self-praising speech about how great he is, the General looks pained. Klink sees this. "Oh, another one of your headaches. Is there anything you can take for that?" "Yes, I can take my leave." The General wants to see this surprise before he has to hear any more of this babble from Klink.

In the barracks, the two look at the gonculator. It's clear that neither knows what a gonculator is, but will not let on to the other that they don't know. Both claim that it looks different from the German version, which the General says is what had him fooled for a second into not knowing what it was. Burkhalter keeps asking Klink to tell him how it's different from the German version and Klink counters with "I wouldn't dream of pointing out something that you know far better than I do." This verbal game of hot potato goes on until Burkhalter orders Klink to make a report to headquarters. Klink then suggests that they let Hogan finish it and then grab the machine - fast thinking to get him out of writing a report on something he knows nothing about! (And I don't think Colonel Johann Schmidt could help him much!)

Schultz keeps an eye on the men to see what they do with the gonculator. Hogan's men know this, of course. So they start messing with him. While he's watching, Newkirk asks LeBeau, who is out of Schultz's sight behind the gonculator, for a light for his cigarette. LeBeau does it in such a way that Schultz thinks the gonculator lit the cigarette. He relays this back to Klink, who tells him to report every move they make.

Klink then gets on the phone to Captain Dingel, the supply officer in the supply depot. Klink asks him for information about the gonculator. Dingel starts frantically looking for information on this non-existent piece of equipment. Dingel asks for the model number Klink is looking for. Klink wants general information. Dingel then has the bright idea to tell him that the gonculator is classified top secret, and that information cannot be given out. This satisfies Klink, and Dingel continues to look after hanging up. Burkhalter then calls and asks for the same thing. Dingel tells him that it's top secret as well. After hanging up he frantically searches (in vain, of course) for information on something that is suddenly very popular.

Back in the barracks, Hogan needs some more parts to keep building the gonculator up. Kinch ran out of radio parts, but has the parts from an old alarm clock that he took apart. Carter takes a piece and asks "Hey Colonel, where should I put this?" "Carter, What difference does it make!"

With Burkhalter back in camp, demanding that they let Hogan finish this so that they can see the American gonculator, Hogan springs his plan. He loudly claims that they can't finish it without the Lutz diagram. They keep repeating it until Schultz reports it back to Klink. Klink remembers hearing aobut Major Lutz the electronics expert and the General makes a phone call to get him in camp right away. With that taken care of, Newkirk asks if they need Schultz anymore. WHen Hogan says no, Newkirk heads to the window where Schultz is listening and throws a bucket of water in his face, "by accident" of course!

When Major Lutz gets to camp, he's sure that he's been found out. He keeps wondering why they would want him. Klink and Burkhalter keep mentioning the Lutz diagram and the gonculator, but he doesn't know anything about a gonculator. They take him to the barracks and show him the homemade gonculator.

When Klink mentions that this is a gonculator, Hogan counters with "That's not a gonculator, it's a toy I made for my little niece Lila." This gets Lutz's attention, and he knows that this is how they are going to get him out of the country ... somehow! Hogan indicates to Lutz that the thing should be plugged in, and Major Lutz orders that it be plugged in. After it is turned on, it sputters for a few seconds and then starts exploding. The lights go out and Hogan gets Major Lutz into the tunnel and bring out a charred German uniform to place on the floor. When the lights come back on, Klink and Burkhalter see the uniform and think that Major Lutz is dead.

Klink is angry, and threatens to throw the book at Hogan. Hogan response with "Who's going to believe that a bunch of prisoners would build a piece of equipment that can only be used on a submarine?" Klink still wants to report the incident to the POW commission of the High Command. Hogan tells him to direct it to the attention of Colonel Johann Schmidt, the officer in charge. Klink then agrees to forget it. (Gee, I wonder why!)

Carter is looking over his now destroyed rabbit trap and notices that he's got a rabbit. After seeing how it looks when told it was going to be hassenpfeffer, he decides to lete it go. It jumps into the rabbit trap and looks at home. Carter wants to keep it. "One rabbit won't be too much trouble, will it Colonel?" "Carter my boy, I must tell you the truth. There is no such thing as one rabbit."